Microwave assisted synthesis of coumarin-purine derivatives: An approach to in vitro anti-oxidant, DNA cleavage, crystal structure, DFT studies and Hirshfeld surface analysis

An easy and efficient microwave-assisted protocol has been developed for the synthesis of coumarin-purine hybrids (3a-3j). The newly constructed 1,3-dimethyl-7-((substituted)-2-oxo-2H-chromen-4-yl)methyl)-1H-purine-2,6(3H,7H)-dione derivatives were evaluated for their in vitro antioxidant activity by DPPH free radical-scavenging ability assay and DNA cleavage by using calf thymus. The compound 3i, shows the most excellent DPPH scavenging activity with a –OH substitution at C7 of coumarin ring. In addition, the structure of compound 3f, has been elucidated using single crystal X-ray diffraction technique. Theoretical calculations (DFT) were carried out using Gaussian09 program package and B3LYP correlation function. Full geometry optimization were carried out using 6-311G++(d, p) basis set and the frontier orbital energy were presented. Hirshfeld surface analysis was used for the intermolecular interactions in the crystal structure. The experimental result of the compound 3f has been compared with the theoretical results and it was found that the experimental data are in a good agreement with the calculated values

Synthesis of coumarin-theophylline hybrids as a new class of anti-tubercular and anti-microbial agents

A series of novel coumarin-theophylline hybrids were synthesized and examined for their anti-tubercular activity in vitro against Mycobacterium tuberculosis H37Rv, anti-microbial activity in vitro against gram-positive bacteria (Staphylococcus aureus) and gram-negative bacterias (Escherichia coli, Salmonella typhi) as well as fungi (Candida albicans). The compound (3a) has shown excellent anti-tubercular activity with MIC of 0.12 μg/mL. Electron donating compounds (3a, 3f) have displayed significant anti-microbial activity. The compounds have also been precisely elucidated using single crystal X-ray diffraction techniques. Molecular docking study has been performed against 4DQU enzyme of Mycobacterium tuberculosis showed good binding interactions and is in agreement with the in vitro results

An Electrochemical Electrode to Detect Theophylline Based on Copper Oxide Nanoparticles Composited with Graphene Oxide

The electrochemical analysis of theophylline (THP) was investigated by fabricating a carbon paste electrode (CPE) modified with graphene oxide (GO) along with copper oxide (CuO) nanoparticles (CuO-GO/CPE). The impact of electro-kinetic parameters such as the heterogeneous rate constant, the scan rate, the accumulation time, the pH, the transfer coefficient, and the number of electrons and protons transferred into the electro-oxidation mechanism of THP has been studied utilizing electrochemical methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The differential pulse voltammetry technique was employed to investigate THP in pharmaceutical and biological samples, confirming the limit of detection (LOD) and quantification (LOQ) of the THP. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were performed to characterize the CuO nanoparticles. The CuO-GO/CPE was more sensitive in THP detection because its electrocatalytic characteristics displayed an enhanced peak current in the 0.2 M supporting electrolyte of pH 6.0, proving the excellent sensing functioning of the modified electrode